Javier Hernandez struck twice for United, opening the scoring from the penalty spot and then doubling the advantage with a header early in the second half.
Phil Jones volleyed the third and substitute Fabio completed the scoring as the game went into 11 minutes of stoppage time.
United have now gone six games unbeaten after a difficult start to the season and assistant boss Steve Round feels momentum is building.
He said: "This club is used to winning, it has a winning mentality.
"There were no great celebrations after the win on Saturday and none tonight.
"We just move on to Fulham, that is how it is.
"You need to go on runs in this league and this club is the best in the business at building that."
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